Autonomous mobility apparatuses are known which autonomously and automatically move along predetermined routes to reach destinations on the routes. Some autonomous mobility apparatuses estimate their current positions and control their moving directions in accordance with the estimated current positions.
Techniques using a Global Positioning System (GPS) are known, which are used by the autonomous mobility apparatuses to estimate their current positions. In acquisition of the current position using the GPS, each autonomous mobility apparatus receives a radio wave transmitted from a GPS satellite that revolves along the orbit of the Earth, and calculates and acquires its current position based on the received radio wave. The autonomous mobility apparatus holds a map indicating its moving route, identifies the current position on the map from information about the current position acquired using the GPS, autonomously moves to a destination while confirming its position on the moving route using the GPS, and reaches the destination.
Such an autonomous mobility apparatus is capable of acquiring the current position using the GPS with high precision. However, when the reception of the radio wave from the GPS satellite is disabled, the autonomous mobility apparatus is not able to acquire its current position and it is difficult for the autonomous mobility apparatus to continue the movement.
For example, the radio wave from the GPS satellite may not be received by the autonomous mobility apparatus well at a location shaded by tall buildings or a wooded location. In this case, a method is proposed in which the autonomous mobility apparatus stops until the reception of the radio wave from the GPS satellite, which has been disabled, is recovered, and the autonomous mobility apparatus restarts autonomous driving if the reception state of the radio wave is recovered within a predetermined time period.
In terms of the technique of the automatic driving on the moving route, for example, a mobile robot disclosed in PTL 1 stores wheel feature values, such as a wheel diameter and a wheel interval, which are set for each section on the moving route composed of multiple sections. The mobile robot calculates the current position based on the wheel feature values set for the section where the mobile robot is currently moving and the amount of revolution of the wheels, which is measured, and reaches a destination based on the calculated current position. The wheel feature values are calculated based on the amount of revolution of the wheels measured between a start point and an end point of the section and measured information, such as the distance of the section and the difference in angle between both ends of the section.
In PTL 2, a vehicle autonomous driving control system is disclosed, which is intended to cause a vehicle to autonomously move using a low-cost sensor such as a differential GPS (DGPS) sensor to reduce the moving difference. This system calculates the azimuth from the difference between positioning signals based on a GPS receiver, calculates the speed and the moving distance based on the numbers of revolutions of left and right driving wheels, calculates the azimuth difference and the moving difference based on comparison between the calculated values and a target route, and calculates the amount of operation of the left and right driving wheels based on the calculated azimuth difference and moving difference to increase or decrease the rotation speed of the left and right driving wheels.